Method and system for wear monitoring using rf reflections

ABSTRACT

In an embodiment, a system for wear monitoring, includes a wear surface, a metallic reflector embedded in the wear surface, a radio-wave transmitter, and a radio-wave receiver. The metallic reflector reflects radio waves transmitted by the radio-wave transmitter for detection by the radio wave receiver. Attenuation of the radio waves between transmission by the radio-wave transmitter and detection by the radio-wave receiver indicates a degree of wear of the wear surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/733,332, filed on Jan. 3, 2020. U.S. patent application Ser. No.16/733,332 is a continuation of U.S. patent application Ser. No.15/730,465, filed on Oct. 11, 2017. U.S. patent application Ser. No.15/730,465 claims priority to U.S. Provisional Patent Application No.62/407,095, filed on Oct. 12, 2016, U.S. Provisional Patent ApplicationNo. 62/417,763, filed on Nov. 4, 2016, U.S. Provisional PatentApplication No. 62/430,400, filed on Dec. 6, 2016, and U.S. ProvisionalPatent Application No. 62/477,228, filed on Mar. 27, 2017. U.S. patentapplication Ser. No. 16/733,332, U.S. patent application Ser. No.15/730,465, U.S. Provisional Patent Application No. 62/407,095, U.S.Provisional Patent Application No. 62/417,763, U.S. Provisional PatentApplication No. 62/430,400, U.S. Provisional Patent Application No.62/477,228 are each incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to surface wear monitoring and,more particularly, but not by way of limitation, to sensors and antennasembedded in equipment having wear surfaces for wear monitoring. In oneembodiment, the disclosure further relates to methods and systems forproviding wear, tear, or rupture status of equipment and items havingwear surfaces such as, for example, conveyor belts and tires. In afurther embodiment, the disclosure relates to the use of RF reflectorsembedded in a belt or tread of a tire and positioned in such a way as tobe impacted by wear while reflecting RF radio waves from an RF radiowave transmitter to a radio wave receiver.

BACKGROUND

Every tire and belt has a means to adapt to host equipment and alife-cycle that starts when the belt or tire is installed and ends whenwear-out limits are reached. If the belts or tires are worn beyond thewear-out limits or damaged, the host may be damaged or become unsafe. Asbelts or tires are used, it is normal for overall belt or tireperformance to change. In addition, irregular belt or tire-tread wearmay occur for a variety of reasons that may lead to replacing a belt ortire sooner rather than later. Regular monitoring of wear condition ofbelts and tires not only provides an indication of when it is time toreplace the belt or tires, it can also help detect other neededmaintenance and get the most value out of the equipment. Presently,monitoring of belt and tire wear is performed manually. What is neededis a method and system that provides automated status updates relativeto wear, tear, or rupture status of equipment and items having wearsurfaces such as, for example, belts and tires.

SUMMARY

Exemplary embodiments disclose a method and system for providingautomated status updates relative to wear, tear, or rupture status ofequipment having wear surfaces such as, for example, belts and tires. Inone embodiment specifically set forth herein, a metallic reflectorembedded in the belt or tread of a tire and positioned in such a way asto reflect RF radio waves from an RF radio wave transmitter and focusthe reflections to a radio wave receiver.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and forfurther objects and advantages thereof, reference may now be had to thefollowing description taken in conjunction with the accompanyingdrawings in which:

FIG. 1 illustrates reflections of RF energy from various types ofsurfaces;

FIG. 2 illustrates a sinusoidal pattern of electrical potential of an RFsignal;

FIG. 3A-3B illustrate a wear monitoring system having reflectorsembedded into the device being monitored in accordance with an exemplaryembodiment;

FIG. 4 illustrates a conveyor system having steel cables embeddedtherein in accordance with an exemplary embodiment;

FIG. 5 is a cross-sectional view of a steel cord conveyor belt system inaccordance with an exemplary embodiment;

FIG. 6 is a cross-sectional view of a torn conveyor belt system inaccordance with an exemplary embodiment;

FIG. 7 illustrates front and side views of a serpentine belt monitoringsystem in accordance with an exemplary embodiment;

FIG. 8 illustrates front and side views of a v-belt monitoring system inaccordance with an exemplary embodiment;

FIG. 9 illustrates a wear monitoring system having stationary sensorsand reflectors in accordance with an exemplary embodiment;

FIG. 10 illustrates an alternative embodiment for the physicalimplementation of a reflector tire wear sensor system;

FIGS. 11A-B illustrates an alternative embodiment for the physicalimplementation of a reflector slurry pipe liner wear sensor system;

FIG. 12 illustrates a transmission system using remote dual antennaswith recessed reflectors;

FIG. 13 illustrates the wear path of a tire;

FIG. 14 illustrates a wear path monitoring circuit in accordance with anexemplary embodiment;

FIG. 15A-15C illustrate physical implementation of the sensors withinthe tire in accordance with the embodiment of FIG. 14;

FIG. 16 illustrates an alternative embodiment of a wear path monitoringcircuit; and

FIG. 17A-17C illustrate physical implementation of the sensors withinthe tire in accordance with the embodiment of FIG. 16.

RADIO FREQUENCY REFLECTION FOR NON-FERROUS MATERIAL WEAR SENSING

The following background is presented for a better understanding of theprinciples of the present disclosure. At lower power frequencies, theeffects of ground (such as the surface of the Earth) interact with RFsignals to bend their course of travel. This bending effect allowslower-frequency RF signals, such as those used in radio and television,to follow the contours of the Earth such as, for example, bending alonghills and valleys. As the frequency of the RF signals increase, such as,for example, in the case of microwave signals, this ground effect isless predominant and the signals follow straight courses, regardless ofthe presence of ground objects. Because these signals follow straightlines, they may be blocked by objects such as buildings, hills, or otherstructures. At these higher frequencies, these signals are referred toas line-of-sight signals.

When RF signals contact metallic surfaces, part of the signal energy isabsorbed into the structure and part is reflected. RF energy that isabsorbed is lost in the surface in the form of heat. Incident waves areredirected relative to the angle they strike the surface. Metallicsurfaces can generally be classified as being: flat, convex or concavecurved or rounded or flattened irregular. FIG. 1 depicts the reflectionsof the RF energy for the various types of surfaces: (A) flat, (B) convexcurved and (C) concave curved, (D) irregular curved and (E) irregularflat surfaces.

As RF signals travel, the electrical potential of the signal varies in asinusoidal pattern as depicted in FIG. 2. The signal voltage (V) 201oscillates about a voltage reference point V_(REF) 202 (may be zerovolts). The number of times the signal crosses this reference level inthe same direction (either positive or negative-going, but not both)each second defines the frequency (f) in hertz (Hz). Voltage levels arethe positive peak voltage (V_(P)) 203, the negative peak voltage(−V_(P)) 204 and the peak-to-peak voltage (V_(P-P)) 205. Since, in avacuum, RF signals propagate at the speed of light (c), the wavelength(λ) 206 is defined as the speed of light divided by the signal frequency(λ=c/f). The term signal amplitude generally refers to the level(positive and/or negative) that the signal deviates from V_(REF).

Addressing now Applicant's approach to utilizing RF reflections for wearmonitoring, specific technical aspects are herein presented. Due tophysical, cost and regulatory constraints, there is a range of RFfrequencies that are effective for monitoring wear. Low frequencies havelarge wavelengths. These force reflectors to be very large forreasonable signal strength. This adds to cost and may makeimplementation physically impossible. High frequency RF signals arecostly to generate and are not commonly used in other applications.Government regulations may also impact the frequencies that are chosen.Currently low cost RF components are not readily available above 20 GHz(λ=15 mm). RF wavelengths below 1 GHz (λ>300 mm) are physically harderto implement. Government regulations such as FCC (United States), CE(Europe), etc. limit the frequencies and amplitudes that may be usedwithout a license. Applicants have observed that signals in the 1 GHz to20 GHz range exhibit line-of-sight characteristics and could be usefulfor wear monitoring because reflections will be linear. Signals greaterthan 20 GHz could also be useful when the technology is readilyavailable. As less expensive and higher frequency components aredeveloped, it is desirable to use these due to their smaller wavelengths.

The use of RF signals to monitor the wear in various components such astires, conveyor belts, slurry pipe liners and haul truck bed liners etc.rely on the general behaviors of RF signals described above. Specificimplementations of these concepts will be described in detail below. Thegeneral concept that makes use of RF signals for monitoring is describedhere. When referring to the types of reflections listed above,Applicants will generally relay on flat, concave and irregular surfaces.These break down into general application types as follows:

-   -   Stationary Sensors and Moving Reflectors: Conveyor and drive        belts are a good example of this. The RF transmitter and        receiver are mounted at a fixed vantage point with the belts        having embedded reflectors moving past them.

Wear monitoring is least complicated when RF reflecting structures arenot present. FIG. 3A and FIG. 3B show examples of wear monitoring wherethe reflectors are embedded into the device being monitored for wear301. The device being monitored will be referred to as a belt. As theembedded reflector 302 passes over the antennas 303 and 304, thetransmitted signal 305 is reflected 306 back into the receiver 304, asshown in FIG. 3A. When the reflector 302 is past the sensors, the RFwave passes through the belt 301 and no signal is received. When thewear reaches the sensor it will begin to be worn away and the pulsewidth 307 and amplitude 308 of the received signal will diminish. Asshown in FIG. 3B, the receiver 304 may alternatively be positioned onthe opposite side of the belt 301. In this embodiment, the presence ofthe reflector 302 is detected by a drop in the signal of amplitude 309.Placing embedded reflectors at different levels allows multiple weardepths to be monitored. Placing reflectors in patterns will allowposition of the belt to be determined.

-   -   Applications with embedded structural components that reflect        RF. Good examples of this are conveyor belts with embedded steel        cables and/or steel mesh to add structural strength:

The addition of reflective structural components adds complexity to themonitoring, but it also adds more information to the signal. First,consider the case where steel cables are embedded at regular intervalsto strengthen a conveyor belt. FIG. 4 shows this example. Because thecables 401 are made up of multiple strands of steel wires and thegeneral shape of the cable is convex with respect to RF signalreflections, most of the signals will not be reflected to the receiveras the cable 401 passes over the transmitter 402 and receiver 403 pair.The reflections from the cables will form small signal levels at thereceiver. Depending on whether the antenna orientation corresponds tothat of FIG. 3A or that of FIG. 3B, the strength of signal received bythe receiver will either increase 404 (FIG. 3A orientation) or decrease405 (FIG. 3B orientation) as the reflectors 406 and cables 401 pass overthe antennas. These signals can be processed by the system to determinethe speed and relative position of the belt. In this case, the longerpulses correspond to the wear depth reflectors and the shorter pulsescorrespond to the cables 401.

Consistent with the above, there is now shown and described Applicant'sapproach of wear monitoring for conveyor belts and the like. In oneembodiment, the present method and system may be installed on and withconveyor belt systems, as illustrated in FIG. 5. Installation may takeplace during the belt manufacturing process or in the field as anaftermarket component of the belt. Several radio reflectors, metallicmesh or metallic belt fabric is set at predetermined depths into thebelt 501, along all or some of its width and in an orientationperpendicular, parallel, or oblique to belt movement 502. A transmitter503 conveys radio waves that reflect off of the metal strips 504. Thedirect or reflected (depending again on FIG. 3A or FIG. 3B orientation)radio waves are collected by at least one radio receiver 505 located asto receive reflected radio waves from the transmitter. The radioreceivers 505 are capable of measuring antenna gain. The characteristicsof the radio signal collected by the receiver(s) 505 are altered if wearor damage removes any of the metal strips 504 embedded in the belt or ifthe belt rapidly changes in lateral position (tracking). If excessivewear, damage, or incorrect positioning of the belt is detected, an alarmcan be sent to an operator or the belt may automatically be shut off.Steel cord 506 may run laterally and/or longitudinally through standardbelts at regular intervals. In various embodiments, monitoringreflections from theses reinforcing wires allows for calculation of beltspeed. Metal strips may also be embedded in the belt at a depth and ordistance from the centerline 507 unlikely to wear or be damaged indifferent patterns 508. The shape of radio signal vs. time curvecollected by the receiver 509 from the transmitter 510 is a uniqueidentification code to different points along the belt. Theseidentification reflectors are not continuous in the direction of beltmovement and may have unique dimensions within a single identificationcode. This may be used to pinpoint localized damage and/or clock beltvelocity. With belt velocity, the reflections from two points can beused to determine the distance between those two points and belt stretchmay be determined. Determining stretch across a spliced section of beltallows monitoring the splice's integrity and can be accomplished withthis disclosure as previously described. Belt velocity can be comparedto the tangential velocity of a pulley, which is related to its angularvelocity and radius, or idler roller to determine belt slippage andpulley or idler roller wear. Wear of the belt is expected to be greaternear the middle of the belt so identification codes should be embeddednear the edge of the belt, and wear reflectors near the centerline 507of the belt 501. The explicit orientation of the transmitter andreceiver array does not need to be uniquely specified given that thewear monitoring system may function successfully as described with thetransmitter 503 or 510 and receiver 505 or 509 in many differentrelative positions and orientations, such as the orientations shown inFIG. 3A and FIG. 3B.

In the orientation of FIG. 3B, characteristics of the received radiosignal may also be altered if damage occurs to the belt but notreflectors. This is because the rubber material of the belt attenuatesthe radio signal to some degree. In FIG. 6 for example, if a tear 601 inthe belt 602 occurs along a path 603 that is monitored by thetransmitter 604 and receiver 605, some of the transmitted radio signalwill pass through the open space of the tear 601 with little attenuationand the receiver 605 will realize an increase in signal strength 606.

FIG. 7 illustrates an embodiment of the disclosure that is embedded in amulti-rib serpentine belt 701. Metal reflectors 702 are solid or meshand are embedded at predetermined depths in the ribs of the belt 701. Ifa mesh is used, the mesh spacing must be less than ¼ of the radiotransmitter wavelength in order to effectively reflect radio waves. Thereflectors are staggered in such a way (see A-A′ and B-B′) that a sideview of the belt would appear to show continuous lengths of metalreflectors along the belt. Staggering the reflectors allows the radiotransmitter 703 signal received by receiver array 704 to berepresentative of the condition of multiple belt ribs at any given time.Staggering the reflectors 702 also allows the belt 701 to be moreflexible than if reflectors 702 were continuous along the entire lengthof the belt 701. Decreased attenuation of the radio signal is indicativeof rib damage or wear.

Some belts 801 may only be made with only one rib, as shown in FIG. 8.With such belts, it is an option to embed a single reflector 802 (mesh)along the length of the belt 801. It is also possible to staggerreflectors 802 along the width and length of the belt, as illustrated inFIG. 7. The same transmitter and receiver configuration as previouslydescribed for FIG. 7 may be used with single rib, v-belts.

-   -   Relatively Stationary Sensors and Reflectors: Tires are a good        example of this. The RF transmitter, receiver and reflector all        move together as a single unit within the tire as it rotates.        When the sensor is required to move with the reflector, the        signals only change as wear occurs.

FIG. 9 shows an example of a wear monitor system where the sensors andreflectors 901 are stationary with respect to each other. When thesignal is transmitted, some of the signal bypasses the reflector and islost 902. The RF wave also spreads as it moves. A parabolic reflector901 is used to focus the reflections on the receiver 903. Before anywear of the reflector 901 commences, the signal levels will be thegreatest at the receiver 903. As wear occurs, more of the RF signal willbypass the reflector 901. A properly designed reflector will still focusenough RF energy on the receiver to be detected when the maximum weardepth is reached. This signal amplitude at the receiver will indicatethe progression of wear on the reflector, and thereby indicate the wearon the device being monitored.

Referring now to FIG. 10, there is shown an embodiment for the physicalimplementation of the sensor of FIG. 9 within a tire, slurry pipe liner,haul truck bed liner or hose. In this embodiment, the placement of thesensor within a tire tread is specifically described and, in similarfashion, may be used with the belts described above. As shown in FIG.10, a metallic parabolic reflector 1001 is embedded in the tread 1002 ofthe tire 1003 and positioned in such a way as to reflect radio waves1004 from a radio wave transmitter 1005 and focus the reflections to aradio wave receiver 1006. The transmitter 1005 and receiver 1006 aremounted to a PCB 1007 that is attached to the inside surface 1008 of ametal support ring 1009 within the tire 1003, beneath the tire tread1002. Apertures 1010 are cut through the support ring 1009 to allow thetransmission of radio waves 1004 between the transmitter 1005, thereflector 1001, and the receiver 1006. A bracket 1011 is attached to thereflector 1001 may be used to assist in positioning of the reflector1001 within the tire tread 1002. As the tire tread 1002 wears, the arclength 1012 of the reflector 1001 decreases and the strength of thesignal acknowledged by the receiver 1006 diminishes. The strength of thesignal is therefore a function of the amount of tread wear. In similarfashion, parabolic reflectors may be utilized in conveyor and relatedbelt systems.

Referring now to FIGS. 11A-B, a plurality of metallic reflectors 1101are embedded in a slurry pipe liner 1102 for example at different depths1103. Each reflector 1101 is associated with a transmitting antenna 1104and a receiving antenna 1105. The transmitting 1104 and receivingantennas 1105 are in communication with a PCB 2006 that is mounted in amilled flat 1107 in the outer pipe wall 1108. The PCB 1106 may beprotected by a material 1109 such as PTFE that allows penetration of aradio signal. The transmitting antenna 1104 transmits a radio signalthrough an aperture 1110 in the outer pipe wall 1108 in the direction ofthe reflector 1101. The aperture 1110 may be filled with a material 1111such as PTFE that allows penetration of a radio signal. The radio signalreflects off of the reflector 1101 and is acknowledged by the receivingantenna 1105. The PCB 1106 stores the data from each set of reflector1101 and antennas 1104 and 1105. The PCB 1106 is in communication withanother transmitting antenna 1112 that transmits the information that isstored on the PCB 1106 to the outside of the pipe wall 1108 for uploadto a mobile data acquisition device 1113 such as a handheld computer.The mobile data acquisition device 1113 may also act as the transmitter1104 and receiver 1105. If the pipe liner 1102 containing slurry orother abrasive mixtures 1114 wears to a depth 1115 such that thereflector 1101 is lost, the receiving antenna 1105 will no longerrealize the signal from the transmitting antenna 1104. This loss ofsignal indicates that the amount of wear associated with reflector depth1103 has occurred. The transmitting antenna 1112 may be replaced with awired connection to the data acquisition device 1113.

The same technique shown in FIGS. 11A-B may be used to monitor wear innon-ferrous haul truck bed liners in the same manner described tomonitor pipe liners 1102. In this embodiment, said pipe wall 1108 is ahaul truck bed.

The same technique shown in FIGS. 11A-B may also be used to monitor wearin hoses in the same manner described to monitor pipe liners 1102. Inthis embodiment, the pipe wall 1108 is absent and the PCB 1106 ismounted to the outside of the hose, represented in FIGS. 11A-B by thepipe liner 1102.

Remote Recessed Reflector Antenna

In certain embodiments of the present disclosure, a Remote RecessedReflector Antenna (R³A) design that enables conductive andnon-conductive surfaces to transmit information via, for example, aradio frequency antenna is used for data transmission. The R³A isrecessed into at least one of the conductive and non-conductive surfacessuch that surface topography is not affected. This is accomplishedthrough the use of a recessed cavity that is covered with a dielectricmaterial such as, for example, Polytetrafluoroethylene, (PTFE) availableunder the name Teflon®. According to the exemplary R³A design, thesurface is not functionally or aesthetically hindered by the presence ofa radio transmitter and the transmitter is protected from theenvironment outside of a cavity in which the transmitter is recessed. Inmost prior-art arrangements, both the antenna and the antenna coverprotrude from the surface. Objects that can host the R³A include, forexample, flat and rounded surfaces that are traveled or subject toabrasion by the environment, or aerodynamic forces. The R³A design ismounted in the surfaces of the tire which are least exposed to abrasion,such as the metal support rings, henceforth referred to as “chassis,”that are commonly embedded in the tire during manufacturing.

In other embodiments, data transmission may also be accomplished by theuse of a conventional, non-recessed antenna if the surface it is mountedon is not subject to abrasion or other forces. The antenna may beencapsulated or otherwise covered with materials that will bestwithstand the abrasion. Teflon is an example of one material that may bewell suited since Teflon has low surface friction; is rigid, and doesnot significantly attenuate radio frequency transmissions. Small gapsaround covers made of materials such as PTFE, may be sealed frommoisture using epoxy or other suitable sealants. The size of theaperture used for wireless transmission must be minimized to bestprotect the antenna and associated circuits. One or more antennas may beimplemented for this application, based on the need to radiate andreceive signals in multiple directions.

FIG. 12 illustrates a transmission system using remote dual antennaswith recessed reflectors in accordance with an exemplary embodiment. Anantenna 1201, series and shunt tuning components 1202 and a cableconnector 1203 are mounted on a circuit board 1204 that is positioned inan antenna cavity 1205 with two mounting holes 1206 aligned withthreaded screw holes 1207 in a bottom region of the antenna cavity 1205.The bottom sides of the two screw holes 1206 in the circuit board 1204have exposed annular rings 1208 that are conductively bonded to a steelsurface of the bottom region of the cavity 1205 using anelectrically-conductive compound. This conductive joint between agrounded circuit board 1204 annular rings 1208 extends the circuit board1204 ground plane into a steel chassis 1216. This overall ground planeacts as the reflector for the antenna. Currently, the antennas aremounted on the edges of flat corner surface reflectors. Mounting theantenna 1201 on flat surface corner reflectors is not possible becausethe surfaces 1209 are ‘wear-surfaces’ (the antenna 1201 would beimmediately destroyed) and the surfaces are contoured such that theyhave no corners. Recessing the antenna 1201 into the surface prevents itfrom being destroyed by compression forces and abrasion in the tire.

The antenna 1201 and the circuit board 1204 are further protected with acover 1210 formed of a material such as Teflon that fills the cavity1205 in front of the antenna 1201 and that is attached by means of twoscrews 1211. Connectors 1203 are attached to RF cables 1212. RF cables1212 carry signals to and from the transceiver and processing circuitboard 1213. Dimensions of cavity 1214 allow the radiation pattern 1215to be ninety degrees (or greater, by means of altering these dimensions1214, when practical). This set of cavity dimensions 1214 is specific tothis example and may be altered, as required, for similar embodiments ofthis disclosure.

Redundant Transceiver Wear Sensor for Non-Ferrous Material Wear Sensing

FIG. 13 illustrates a wear-path of a tire. The wear-path is defined asthe path from a surface of a new tire to a wear-out or damage limit thatis to be monitored. Exemplary embodiments disclose a novel RedundantTransceiver Tire Wear Sensor with Remote Recessed Reflector Antenna(RTTWS-R³A) design that enables tires to automatically report wear, tearor rupture status over their life-cycle. This disclosure is, however,not limited to use in tires and may be utilized in any equipment thathas wear surfaces that may benefit from wear monitoring.

In a typical embodiment, the RTTWS-R³A implementation process begins bydefining the wear paths on tires that are to be monitored. Since eachtire has unique characteristics, the wear-paths to be monitored differin both location and wear depth. Wear rate at different points on thetires may vary based on the tires engagement with a ground surface. Forexample, a small tire may only require one wear-path to be monitoredwhile larger tires may require multiple paths or wear-depths (i.e.,distance from new surface to wear-out limit) to be monitored. Accordingto exemplary embodiments, wear depth monitoring is accomplished for eachwear-path by embedding, for example, transducers at intervals along thewear-path. As tire surfaces wear reaches a transducer, itscharacteristics are altered. According to exemplary embodiments, theRTTWS-R³A implementation process includes any type of transducer todetect wear on the tire. The use of resistors as transducers is givenhere as an example. As a tire rotates, the part of the tire thatcontacts the road surface may deflect due to the weight of the vehicle.Such deflection could cause the alignment of the transducers, andparticularly the parabolic reflectors, to deviate enough to cause anerror in the wear-depth calculation. To prevent this, an accelerometeris used to determine the position of the tire with respect to the roadsurface. Signals are sampled with the wear area to be sampled is not incontact with the road surface.

FIG. 14 illustrates a wear path monitoring circuit in accordance with anexemplary embodiment. Although this application is not limited to aspecific type of transducer, the use of stainless steel wires andresistor pairs (i.e., redundant resistors) for monitoring is disclosedherein as an example. A first wire pair SSW1 a/SSW1 b is embeddednearest an outer wear surface. Additional wire pairs SSW2 a/SSW2 bthrough SSWna/SSWnb are equally spaced apart along the wear path. When atire surface wears down or is damaged to a wire in a pair such as, forexample, the wire pair SSW2 a/SSW2 b, the combinatorial resistancechanges. The change in resistance indicates to a processing device thatthe wear depth for the wire pair has been reached. In a typicalembodiment, the processing device may be, for example, a computer, aprocessor, a microcontroller, and the like. Although not shown in thewear path monitoring circuit, the redundancy may be increased, frompairs to groups, by adding more wires. This will decrease theprobability of false indications due to defective wire failures. Moreredundancy may be added by independently returning ground wires to thecircuit board independently.

According to exemplary embodiments, the use of redundant transducers andtraces improve the monitoring reliability of the sensors. Singlecomponent, connection or trace failures resulting from defects inmanufacturing, temperature extremes, shock or vibration of the operatingenvironment are detected and compensated for in the processingcircuitry. For example, if R1 a and R1 b are the same value and theparallel combination of R1 a and R1 b through wire pair SSW1 a/SSW1 bequals the value of R1, the analog voltage detected at the an input ofthe processing device is V/2. If a failure of wire SSW1 a or wire SSW1 bor a connection or wiring to either of these resistors results, due to amanufacturing, material fault, temperature extremes, shock or vibration,one of the resistors will be omitted from the circuit. This will resultin the resistance of R1 being ½ the resistance of the remainingconnected resistor (R1 a or Rib). The voltage detected at the input willthen be V/3. This voltage level will indicate to the processor that thefailure may not be related to wear. If the voltage level is due to wear,it will not make a difference. The other wire in the pair will soon beremoved by wear. Until both wires in the pair are faulted, thewear-point will not be considered to have been reached. In sensors thatdo not have redundancy, failures in any of the traces or transducerwould incorrectly indicate that the wear point was reached.

FIG. 15A-15C illustrate physical implementation of the sensors withinthe tire in accordance with an exemplary embodiment. The physicalimplementation of the sensor wires 1501 and communication wires 1502 maybe accomplished by embedding the sensor wires 1501 and the communicationwires 1502 in the tread during a vulcanization process. A communicationelement 1503 may be installed in a tire 1504 inside of a tirecomponentry such as, for example, a chassis 1505 during a manufacturingprocess, prior to vulcanization, or optionally outside of the tirecomponentry in the tread during the vulcanization process. The physicalpaths of the circuitry and communication cable may be perpendicular 1506to the chassis 1505 and/or at an angle to the chassis 1505. In someembodiments, the tire 1504 may be embedded with a single wire pair. Inother embodiments, the tire 1504 may be embedded with multiple wirepairs. For exemplary illustration, numerous wire pairs are shown in FIG.15A-15B.

The redundant wire pairs SSW1 a 1507, SSW1 b 1508, SSW2 a 1509, SSW2 b1510, SSWna 1511 and SSWnb 1512 are shown with an exaggerated scale andlayout in a small segment of a tire. Wires are routed within the treadsuch that the steel flexes within its elastic limits to avoid metalfatigue, allowing the wires to remain intact until they are broken bytire wear. All sensor wires route to processing element 1513. In atypical embodiment, data is formed into packets and transmittedwirelessly 1514 inward towards at least one of a center of the tire,outward from the center of the tire, or radially out of the tire, to ahost which is generally located on a vehicle. FIG. 15A-15C illustratethree different depths of wire sensors. Exemplary embodiments discloseimplementations from one sensor wire pair to any number or wear depthsand sensor array configurations.

FIG. 16 illustrates a wear path monitoring circuit in accordance with analternate embodiment using resistor pairs (i.e., redundant resistors).T1 is embedded nearest an outer wear surface with T2 through Tn equallyspaced along the wear path. Tn is located closest to the wear limit.When a tire surface wears down to a resistor pair such as, for example,R1 a and R1 b, the combinatorial resistance changes. The resistance canbe reduced or shorted (if filled with mud) or increased or open (if theconnections or resistor are damaged or broken). The change in resistanceindicates to the processing device that the wear depth for the resistorpair has been reached. Although not illustrated, the traces may also bemade redundant by use of more traces installed on flexible circuit boardlayers to decrease the probability of false indications due to faultytrace failures.

Redundant transducers and traces improve monitoring reliability of thesensors. Single component, connection or trace failures resulting fromdefects in manufacturing, extremes in temperature, shock or vibration ofthe operating environment are detected and compensated for in theprocessing circuitry. For example, if the parallel combination of R1 aand R1 b equals the value of R1, the analog voltage detected at theprocessor input is V/2. If a failure of R1 a, R1 b or a connection ortrace path to either of these resistors results, due to a manufacturingfault, temperature extremes, shock, or vibration, one of the resistorsis omitted from the circuit. This results in the resistance of R1 being½ the resistance of the remaining connected resistor such as, forexample, R1 a or R1 b. The voltage detected at the input will then beV/3. This voltage level will indicate to the processing circuitry thatthe failure may not be related to wear. If the voltage level is due towear, it will not make a difference. The other resistor will soon beremoved by wear. Until both resistors in the pair are faulted, thewear-point will not be considered to have been reached. In sensors thatdo not have redundancy, failures in any of the traces or transducer willincorrectly indicate that the wear point was reached.

FIG. 17A-17C illustrate physical implementation of the sensors withinthe tire in accordance with an alternate embodiment. The physicalimplementation of the sensor wires 1701 such as, for example, wires andredundant resistor pairs imbedded in flexible PCB and communicationwires 1702 to the processing and communication element 1703 may beaccomplished by embedding them in the tread during the vulcanizationprocess as is presently done with RFID circuitry. The processing andcommunication element 1703 may be installed inside the tire componentsurfaces 1706 (e.g., the “chassis”) during the manufacturing processprior to vulcanization, or outside of the tire componentry (the“chassis”) and in the tread 1704 and installed during the vulcanizationprocess. The physical paths of the circuitry and communication cable maybe perpendicular to 1706 and/or at an angle to the chassis 1706.

The transducers T1 1707, T2 1708, and Tn 1709 are shown with exaggeratedscale and layout in a small segment of a tire. Wires are routed withinthe tread to redundant resistors on flexible PCB such that the steel andPCB flexes within its elastic limits to avoid metal fatigue, allowingthe wires and PCB mounted resistors to remain intact until they arebroken by tire wear. All sensor wires route to processing element 1710which can be mounted in the tread during the vulcanization process, oroutside of the tread as shown. The data is formed into packets andtransmitted wirelessly 1711 inward towards the center of the tire and/oroutward from the center of the tire or radially out of the tire to thehost which is generally located on the vehicle. The diagram shows 4different depths redundant wear sensors. Exemplary embodiments discloseimplementations from one sensor pair to any number or wear depths andsensor array configurations.

From the perspective of monitoring the wear of a tire, since there areno practical means of attaching wires from the tire to the vehicle forcommunication, the application is considered to be remote. Themonitoring electronics are embedded in the rotating tire. Sending thesignals to the operator is a challenge. For the tire, the monitoringelectronics inside the tire are powered by a battery. These batteriesare to be specified to operate the monitoring circuits for the lifetimeof the tire. When the tire is installed on the machine, the monitoringprocessor may be activated (awakened) from a ‘deep sleep’ mode andremains active for the life of the tire or may only be active when thetire rotates.

Referring now to power aspects for the embodiments shown and describedherein, the use of a battery with the methods and systems of the presentdisclosure is optional if piezoelectric ceramic wafers (PCW's) areimplemented into the circuitry. PCW's develop small voltages when theyare subjected to vibrations that excite them to move at their resonantfrequencies. State of the art devices have now been developed to convertthese small voltages into energy sufficient to power small sensors andtransmitters. This type of technology is being called “energyharvesting”. The currents harvested from these devices are used tocharge electrical storage devices such as capacitors, super capacitorsand potentially batteries. When sufficient energy has been stored toread the transducers and transmit the data in a wireless packet, thedata is transmitted to the host. This disclosure may be applied to tirewear monitoring using the tire rotation and vibration to excite the PCW.

General Computing and Computer Programming Disclosure

Particular embodiments may include one or more computer-readable storagemedia implementing any suitable storage. In particular embodiments, acomputer-readable storage medium implements one or more portions of theprocessor, one or more portions of the system memory, or a combinationof these, where appropriate. In particular embodiments, acomputer-readable storage medium implements RAM or ROM. In particularembodiments, a computer-readable storage medium implements volatile orpersistent memory. In particular embodiments, one or morecomputer-readable storage media embody encoded software.

In this patent application, reference to encoded software may encompassone or more applications, bytecode, one or more computer programs, oneor more executables, one or more instructions, logic, machine code, oneor more scripts, or source code, and vice versa, where appropriate, thathave been stored or encoded in a computer-readable storage medium. Inparticular embodiments, encoded software includes one or moreapplication programming interfaces (APIs) stored or encoded in acomputer-readable storage medium. Particular embodiments may use anysuitable encoded software written or otherwise expressed in any suitableprogramming language or combination of programming languages stored orencoded in any suitable type or number of computer-readable storagemedia. In particular embodiments, encoded software may be expressed assource code or object code. In particular embodiments, encoded softwareis expressed in a higher-level programming language, such as, forexample, C, Python, Java, or a suitable extension thereof. In particularembodiments, encoded software is expressed in a lower-level programminglanguage, such as assembly language (or machine code). In particularembodiments, encoded software is expressed in JAVA. In particularembodiments, encoded software is expressed in Hyper Text Markup Language(HTML), Extensible Markup Language (XML), or other suitable markuplanguage.

Conditional language used herein, such as, among others, “can,” “might,”“may,” “e.g.,” and the like, unless specifically stated otherwise, orotherwise understood within the context as used, is generally intendedto convey that certain embodiments include, while other embodiments donot include, certain features, elements and/or states. Thus, suchconditional language is not generally intended to imply that features,elements and/or states are in any way required for one or moreembodiments or that one or more embodiments necessarily include logicfor deciding, with or without author input or prompting, whether thesefeatures, elements and/or states are included or are to be performed inany particular embodiment.

While the above detailed description has shown, described, and pointedout novel features as applied to various embodiments, it will beunderstood that various omissions, substitutions, and changes in theform and details of the devices or algorithms illustrated can be madewithout departing from the spirit of the disclosure. As will berecognized, the processes described herein can be embodied within a formthat does not provide all of the features and benefits set forth herein,as some features can be used or practiced separately from others. Thescope of protection is defined by the appended claims rather than by theforegoing description. All changes which come within the meaning andrange of equivalency of the claims are to be embraced within theirscope.

1. A system for wear monitoring, comprising: a non-metallic surface;integrated metallic shapes embedded at pre-determined depths in thenon-metallic surface; focused radio-wave transmitters positioned at afirst angle relative to the non-metallic surface and transmittingfocused radio frequencies; focused radio-wave receivers positioned at asecond angle relative to the non-metallic surface; wherein thenon-metallic surface and the integrated metallic shapes produce asignature of radio waves transmitted by the focused radio-wavetransmitters, the signature of the radio waves diminishing in signalstrength as the non-metallic surface wears; and wherein detection of thesignature of the radio waves from the focused radio-wave transmitters bythe focused radio-wave receivers is averaged over time to establish acondition of the non-metallic surface to infer wear.
 2. The system ofclaim 1, wherein the non-metallic surface is a tire.
 3. The system ofclaim 1, wherein the non-metallic surface is a liner for transport ofabrasive materials.
 4. The system of claim 1, wherein the integratedmetallic shapes are parabolic.
 5. The system of claim 1, wherein thefirst angle and the second angle are different.
 6. The system of claim1, wherein the non-metallic surface, the focused radio-wavetransmitters, and the focused radio-wave receivers are stationaryrelative to each other.
 7. The system of claim 1, wherein the focusedradio-wave transmitters and the focused radio-wave receivers arepositioned relative to a wearing side of the non-metallic surface. 8.The system of claim 1, wherein the focused radio-wave receivers detectthe radio wave signatures of the integrated metallic shapes where thenon-metallic surface is prone to wear to identify the degree of changein the size or the presence of the integrated metallic shapes over timeand therefore the degree of wear of the non-metallic surface.
 9. Thesystem of claim 1, wherein: the focused radio-wave receivers detectattenuation of the radio waves through the non-metallic surface; and adegree of change in the attenuation of the radio waves through thenon-metallic surface over time is averaged to map the condition of thenon-metallic surface to infer wear.
 10. The system of claim 1, whereinthe focused radio-wave receivers do not detect any radio wave signaturesfrom artifacts, the integrated metallic shapes, or the non-metallicsurface, indicating that the non-metallic surface is at least one ofseparated, torn, or damaged.
 11. The system of claim 1, wherein theintegrated metallic shapes are at least one of parabolic, round, andrectilinear.
 12. The system of claim 1, wherein the integrated metallicshapes are at least one of installed during a manufacturing process ofthe non-metallic surface and installed at any time following themanufacturing process.
 13. The system of claim 1, wherein thenon-metallic surface is a solid load bearing pulley or wheel.
 14. Thesystem for wear-monitoring of claim 1, wherein the non-metallic surfaceis a solid cable guide.
 15. The system of claim 1, wherein the focusedradio-wave receivers detect radio wave signatures of artifacts foridentification of reference position and for tracking of at least one ofchanges in lateral position, excessive vibration, linear speed, damage,and stretch of the non-metallic surface.